Biology subjects

Hensen, N.

Publications and source records attributed to Hensen, N..

3 recordsLinked to original sources

bioRxiv2026

Elevated substitution rates and increased purifying selection associated with thermophily in Chaetomiaceae fungi

Understanding the genomic consequences of thermal adaptation in fungi is crucial, as rising global temperatures are expected to have negative impacts on food safety and human health. The family Chaetomiaceae contains a large number of thermophilic fungal taxa, but previous studies have reported inconsistent optimal growth temperatures (OGT) for the same strains, obtained with various laboratory methods. Here we applied a standardized laboratory approach to measure OGT across strains of 17 Chaetomiaceae species and used a phylogenomic approach to test associations between OGT, rates of genome evolution, and strength of purifying selection. Compared to mesophiles, thermophilic fungi showed faster nucleotide substitution rates. In addition, thermophiles showed lower dN/dS ratios than mesophiles, suggesting stronger purifying selection on conserved orthologs. We hypothesize that the elevated substitution rates are linked to high growth rates, as thermophilic fungi grew significantly faster than mesophilic ones. Our results show that selective pressures may act at different temperatures for distinct genomic characteristics. Genome size was lower at OGT [≥] 35{degrees}C compared to mesophilic species, while GC content did not show a large difference between mesophiles and thermotolerant species, but increased in thermophilic species with an OGT [≥] 45{degrees}C.

evolutionary biology↗

bioRxiv2026

Living in a metal-rich world: Enhanced growth and reduced metal accumulation in Fusarium fungi from the Kiirunavaara iron ore mine

BackgroundHuman activities such as mining generally lead to increased heavy metal concentrations in the environment. While traditional remediation techniques are often costly, the use of fungi as bioremediators, known as mycoremediation, is increasingly gaining attention as a sustainable approach for removal of heavy metals. Here, we evaluated heavy metal levels inside the Kiirunavaara iron ore mine in Northern Sweden and analysed fungal responses to various metal concentrations by comparing growth and metal uptake in mine-derived isolates and closely related control isolates. ResultsSediments inside the mine were enriched in heavy metals compared to those from the outlet of the mine to natural lakes. Six Fusarium isolates were recovered from contaminated mining environments: five isolates from inside the mine were identified as Fusarium oxysporum, and one isolate from the outlet was identified as Fusarium tricinctum. Isolates from the mine and outlet showed overall higher survival and biomass production in presence of copper, iron, and zinc across a range of concentrations (up to 1000 mg/L) compared to control isolates. At the same time, these isolates often exhibited reduced relative metal uptake. As a result, mycoremediation potential, assessed as total uptake in the grown mycelium, was isolate-dependent. ConclusionsBased on these results, we conclude that Fusarium isolates from the Kiirunavaara mine show increased growth in media enriched with heavy metals compared to closely related control isolates. We additionally show that mycoremediation potential is not necessarily associated with environmental origin. Instead, mycoremediation potential should be evaluated on a case-by-case basis for each isolate and based on specific needs for mycoremediation.

microbiology↗

bioRxiv2025

Patterns and drivers of genome-wide codon usage bias in the fungal order Sordariales

Here we present a study on amino acid composition, codon usage bias (CUB), and levels of selection driving codon usage in Sordariales fungi. We found that GC ending codons are used more often than AT ending codons in all Sordariales genomes, but the strength of CUB differs amongst families. The families Podosporaceae and Sordariaceae contain relatively low genome-wide levels of CUB, while the highest levels of CUB are found in Chaetomiaceae and the "BLLNS"-group, a monophyletic group of five other Sordariales families. Based on genomic clustering, and ancestral state reconstruction of GC nucleotides at the third codon position, we hypothesize that Podosporaceae and Sordariaceae represent the ancestral state of amino acid composition and CUB. The Chaetomiaceae and BLLNS have most likely diverged from this state, with increased natural selection driving use of specific codons, resulting in higher genome-wide CUB. We expect that the higher levels of CUB in Chaetomiaceae genomes might have been caused by ecological niche specialization, including high optimal growth temperature of some Chaetomiaceae species.

genomics↗